1. Field of the Invention
This invention relates to transportable tanks for storing and dispensing liquids. More specifically, this invention relates to a system for withdrawing liquids from multiple storage compartments on board vehicles or equipment.
2. Description of the Prior Art
A variety of vehicles and equipment carry multiple liquid storage compartments that experiences pitch and/or yaw motion during transport. This motion affects the relative liquid level between the compartments and can interfere with liquid removal from the compartments. Common examples of such compartments can be found in agricultural spray equipment and vehicle fuel tank arrangements. The use of multiple fuel tanks or fuel storage compartments on motorized vehicles is well known. In these systems, the multiple compartments or tanks are often horizontally spaced along the axis of the vehicle or on different sides of the vehicle. In order to withdraw fuel from all the compartments, conduits or passageways typically interconnect the compartments. An arrangement of this type is shown in U.S. Pat. No. 3,311,183, issued to Phillips, wherein a large conduit connects a pair of saddle tanks for an agricultural tractor. Phillips teaches the use of a large conduit to connect the bottom of two saddle tanks which allows liquid flow from one compartment to the next. Fuel is then withdrawn from one compartment having a fuel withdrawal line or withdrawal point at its bottom.
Connecting multiple tanks with a single conduit at the bottom of the tanks functions very well as long as the tanks are maintained relatively level. When level, the tanks are all emptied at approximately the same time so that the vehicle can use all available fuel. However, when off-level, a large portion of fuel may be trapped in a portion of the tank inclined below the fuel withdrawal point. Therefore, although plenty of fuel may be available in the tanks, the engine may run out of fuel while the vehicle is operating off-level.
This problem is particularly troublesome for agricultural or industrial vehicles having dual tanks or elongated tanks. These vehicles often operate for extended periods of time in an off-level condition. When operating off-level, the tank geometry can greatly reduce the volume of available fuel. This situation affects single compartmentalized tanks or multiple tanks and occurs with a forward and back or sideways angle of the inclination.
Looking specifically at tractors, these vehicles are often used on hillsides and operate for long periods of time while tipped to one side. As a tractor continues to move back and forth on a slope, the angle will be reversed when the tractor reaches the end of a pass and begins its way back. A number of tractors use saddle tanks mounted crosswise on opposite sides of the tractor as shown in U.S. Pat. No. 3,311,183. Fuel is withdrawn from the bottom of one of the tanks at a point closest to the tractor body. Thus, when off-level operation raises the tank having the fuel withdrawal nozzle, a large quantity of fuel can be trapped in the other side tank below the level of the fuel withdrawal inlet. Depending on the tank geometry and inc1ine, it is possible for the tractor engine to run out of fuel with as much as 1/4 or more of the total fuel volume still remaining in the tanks.
A dual tank arrangement designed to provide complete fuel recovery is shown in U.S. Pat. No. 4,288,086 issued to Oben et al. In this arrangement, a pump transfers fuel from the bottom of an auxiliary tank to the top of a main tank in response to a signal from a level sensor in the main tank. Fuel for the engine is withdrawn from the bottom of the main tank. Although the '086 invention can provide additional fuel utilization during off-level operation, the pump and level sensor adds complexity to the fuel system. In addition, the pump will sequentially empty the tanks which, particularly in a side mounted tank arrangement, unbalances the vehicle.
It is an object of this invention to provide a tank assembly for liquid storage that will increase the quantity of fuel available for withdrawal during off-level operation without the addition of pumps or sensors.
It is a further object of this invention to provide a dual fuel tank arrangement with increased fuel availability during off-level operation that will limit the load imbalance imposed on the vehicle.
A yet further object of this invention is to provide a tractor side tank assembly that will minimize the amount of fuel that is not withdrawable from the fuel tanks during off level operation of the vehicle.